Multidose jet injector



April 28, 1964 A. VENDITTY ETAL MULTIDOSE JET INJECTOR 2 Sheets-Sheet 1 f %VENT(?R$J Z a? ATTORNEYS.

@a W f f m m. a I wa w a m /m .\l x M P w m \KIIW?! 4 a w m 6 g w f 4 United States Patent 3,130,723 MULTIDOSE JET INJECTOR Anthony Venditty and Alfred W. Kath, Detroit, Mich, assignors to R. P. Scherer Corporation, Detroit, Mich., acorporation of Michigan Filed Aug. 15, 1960, Ser. No. 49,662 11 Claims. (Cl. 128-173) This invention relates to a hypodermic injector capable of administering one injection after another in rapid sequence. Such instruments eject a high velocity jet stream through a tiny orifice in the end of the instrument. The orifice is placed in tight contact with the skin. The very small, high velocity jet stream has the ability to penerate the epidermis so that the liquid medicament following the initial portion ejected will flow into the tissue beneath the epidermis. The instrument finds particular use for mass inoculations. A reservoir is carried by the body of the instrument to replenish the liquid medicament chamber within the instrument after each ejection. The instrument can be operated in accordance with the principle set forth in Patent No. 2,754,818, dated July 17, 1956, that is, the discharge from the orifice may be effected at two diflererit prmsure stages sequentially. The initial high pressure stage produces a very small puncture through the epidermis and the second lower pressure or follow-through expels the remaining liquid into the underlying tissue through the puncture.

A primary object of the invention is to provide a simplified multidose unit made from a minimum number of parts most of which arereadily accessible from staple hardware stock. In this respect the instrument of the present invention is superior to that disclosed in Patent 2,928,390 which is designed to accomplish the same objective. The present instrument is also much less expensive to manufacture because of the small number of standard parts.

Another object is to provide a novel means for propelling the plunger which expels the liquid medicament from the chamber. This means utilizes an expanding spring in combination with pressurized fluid. The spring provides the initial high magnitude force and the fluidized pressure provides the lower force for follow-through.

Another object is to provide an injector of this type in which a precompressed spring is additionally compressed by the force of the pressurized fluid prior to discharge of the instrument, the additional compression in the spring providing the force necessary for the high velocity stage.

Another object is to provide a movable piston sealed within the cylindrical body by means of a flexible diaphragm, thus permitting the piston to move within the body with a minimum of friction. Unlike sealing gaskets and O-rings, the flexible diaphragm rolls as the piston moves and because there is little or no wear, it is long lasting and durable.

Another object is to provide an instrument in which the position of the plunger within the medicament chamber may be regulated to provide varying dosage.

A further object is to provide an instrument of this type in which the plunger carries a detachable head which moves relative to the plunger proper and may be spaced therefrom. Under the initial force imparted to the plunger proper by the spring, it moves forward a short distance to pick up speed before striking the spaced head.

The distance between the head and the plunger is less,

3,130,723 PatentedApr. 28, 1964 will become apparent from the following description which illustrates a preferred form of the invention. In the drawings:

FIGURE 1 is a perspective view of an instrument constructed in accordance with the invention;

FIGURE 2 is a front plan view of the instrument shown in FIGURE 1;

FIGURE 3 is a side elevational view showing the body of the instrument in cross section and the plunger in retracted position;

FIGURE 4 is a view similar to FIGURE 3 showing the plunger in advanced position; and

FIGURE 5 is a detailed view of the detachable plunger head partly in section.

The main body 10 of the instrument is cylindrical in shape and is supported on a handle or grip 60 having an integral supporting cradle 62 which embraces the underside of the cylindrical body. The handle is secured to the body by means of screws 64 and consists of two complementary parts 61 which are longitudinally split to permit manufacture and assembly. The two parts 61 are secured together by means of screws 63. The forward end of the instrument terminates in a valve body which takes the form of a cylindrical block 14. The cylindrical block 14 carries a pin 20 in the top thereof which is adapted to slide in a. way 22 for locating the block 14 Within the body 10. Bored into the right end of the block 14, as best shown in FIGURE 3, is a medicament chamber 18. A collar 16 screws onto the external threaded portion 12 of the body to hold the block 14 in position. The block 14 has a circumferential flange 41 to receive thrust of collar 16 to abut the end face of block 14 to the face of ring 109 which in turn abuts against shoulder 111 of body 10 when the block is assembled. It will be noted that the body is of lesser diameter at the forward end 12 so that the collar 16 is approximately flush with the outside of the body. The forward end of the block 14 terminates in a threaded projection 48 onto which the nozzle 46 is screwed. Nozzle 46 has a tiny orifice 52 through which the medicament is ejected in the form of a fine jet stream. A'cap 54 may be placed over the nozzle to keep it sterile.

Communication from the medicament chamber 18 to the nozzle orifice 52 is through the central conduit or bore 43 extending axially through the block 14, A transverse bore through the block aligned with the bore 43 carries a rotary valve 40 having ports 44 and 42. When the instrument is ready for firing, the rotary valve is in the position shown in FIGURE 4 with the port 42 aligned with the bore .01 conduit 43. The port 44 is shut off. When it is desired to replenish the supply of liquid medicament in the medicament chamber 18, the rotary valve is turned to the position shown in FIGURE 3, thus establishing communication between the medicament chamber and the conduit 27 in the L-fitting 26 screwed into the threaded opening 24 in the top of the block 14. The totary valve member 40 is held in place by means of a screw secured in the end thereof and the opening is sealed by -O- rings 141 at either end of the valve member. A handle 146 is secured to the other end of member 40 and comprises the sleeve portion 142 and stop members 144, the purpose of which will be described below.

The liquid reservoir for carryinga large quantity of medicament takes the form of a bottle 34 held on the instrument by means of the spring metal clamp '36. The clamp is held to the top of the instrument by means of screws 38. A hypodermic needle 28 is adapted to pierce the stopper in the end of the .bottle 34 to establish communication between the interior of the bottle and the opening 27 within the L-fitting 26. A standard hypodermic needle is employed having the conventional hex head which is disposed Within one end of the L-fitting 26. In

order to provide a venting for the interior of the bottle 34,

an additional hypodermic needle 39 having a conventional head 32 is soldered to the needle 23 and projects through the stopper into the bottle 34. The head 32 of the needle 3% may be packed with sterile cotton or other medicinally-treated material which filters out any bacteria from the air which enters the bottle to replace liquid.

Medicament is expelled from the chamber 18 by means of the plunger head 74 which is detachably connected to the plunger proper identified generally by the numeral 72. The plunger in turn is linked to piston 70 slidably mounted in the rear of the body It). A precornpressed spring 78 is interposed between the plunger '72 and the piston 70. Pressurized fluid is introduced into the end of the instrument through the fitting 136 for additionally compressing the spring and advancing the plunger.

Referring now to these parts in more detail, the rear of the body, shown at the right side of FIGURES 3 and 4, is enclosed by means of an end fitting 15 which has a centrally projecting nipple 17 into which the angular fitting 135 is screwed. The fitting 136 has an internally threaded opening 138 for receiving a hydraulic fluid hose 139, the other end of which connects to a source of pressurized fluid, preferably mineral oil. The fluid source is not shown in the drawing. Such devices are well known, the form shown in Patent 2,928,390 being suitable for use in this invention. The end fitting 15 is secured to the body by means of a collar 13 which screws onto the external threads 11 provided at the end of the body. It will be noted that the fitting 15 has a circumferential recessed inner edge which clamps the bead 82 of the annular diaphragm 80 against the end of the hollow body 10. The diaphragm 80 extends radially inwardly in the form of an annular loop 69 and is secured to the piston 7i) by means of a T-plug 81 which screws into the threaded opening 85 in the end of the piston 70. The head of plug 81 bears against a washer 83 which in turn applies pressure to the marginal edge of the diaphragm 80. A screw 86 is disposed within the plug 81 and constitutes an adjustment to position the plunger with respect to the latch 1249 described below. The screw also prevents partial stripping of the plunger head 74 from the plunger due to strong retraction of the plunger. Some adjustment is required to compensate for manufacturing tolerances.

'Thus, the position of the plunger head 74 within the medicament chamber 18 may be regulated before the instrument is completely assembled. The diaphragm 80 is made from fabric-reinforced rubber and is looped within the space between the piston 70 and the internal wall of the body it). As the piston 70 moves within the body, the diaphragm rolls back and forth, decreasing and increasing the length of loop 69 with a minimum of friction between the moving parts. The head 71 of piston 70 is the only portion that touches the body wall. This construction has been found to be particularly useful in this instrument since it is much more durable than rings, gaskets or similar packings which are normally used between a piston and its cooperating cylinder. The seal between the body and the piston is complete and efficient and prevents any hydraulic fluid from moving past the piston into the forward end of the instrument.

The plunger 72 terminates at its left or forward end in a detachable head 74 which is inserted in a central bore 92 extending through the plunger. At its right or rearward end the plunger is of increased diameter and forms a cup-like spring seat 76 adapted to receive the spring 78. The seat has a flange 75 which runs in contact with the inner wall of the body 10, but is otherwise spaced from the wall. A link 90 which takes the form of a bolt connects the piston 70 with the plunger 72. The head of the bolt lies within the opening 85 in the piston 74) and bears against the flange 87 at the forward end of the piston. The shank of the bolt is threaded at the left end and screws into the threaded opening 92 in the plunger. By turning the link 90, the distance X between the piston 70 and the end of the plunger '72 may be accurately adjusted. The spring '78 is precompressed from 1 /2 to about 1" and held in compressed position by the linking bolt 90. The spring is designed for maximum life and is of the high rate type which in its precompressed condition exerts a force of around 290 pounds. An additional 20 to 30 pounds is required to compress the spring the distance X.

The assembly of the head 74 with the plunger proper 72 is best illustrated in FIGURE 5. The nose of the head is adapted to fit accurately the funnel-like end of the medicament chamber 18 so that all of the medicament is expelled when the plunger is in fully advanced position. A circumferential groove 98 in the outer wall of the plunger head is designed to carry an O-ring 100 which is enclosed in a Teflon ring 1102. This combina= tion gasket bears against the wall of the medicament chamber and prevents any fluid from by-passing the plunger and escaping into the body. The plunger shaft 106 is screwed into a threaded opening 164 in the end of the plunger head. The shaft 106 is split to provide an opening 197 so that the two fork-like halves formed thereby may be compressed toward each other to per- Init insertion and removal of the plunger head 72 from the end 96 of the plunger 72. The shaft 106 is of larger diameter at its right end as indicated at 108 so that the projecting surface will bear laterally against a corresponding shoulder of sleeve 95 Within the opening through the plunger 72. The plunger head is assembled with the block 14 disposed in the forward end of the instru ment and when this block is removed, the head separates from the plunger 72 by reason of the spring shaft which compresses as it is pulled from the opening through the plunger. A stripping ring 109 is mounted on the flange lit) which projects from the rear end of the block 14. The inner diameter of the ring 199 is smaller than the diameter of the medicament chamber 118. Consequently, the outside diameter of the plunger head 72 abuts against the side of the ring 109 when the block is removed. Consequently, the plunger head is caused to remain with the block 14- when the blo-ck 14 is removed from body 10. The ring M99 has an opening on one side so that it will slip over the projecting flange 110 like a horse collar. Interposed between the spring seat 76 and the stripper ring W9 is a retracting spring 94- which is adapted to push the plunger 72 and the piston 70 toward the rear of the instrument after an injection has been made. Washers 93 and 97 are provided against the faces of the spring seat 76 and the body shoulder 111, respectively, to provide bearing surfaces against which the spring 94 abuts. The washer 93 also serves as a wear resistant surface for stop surface 132 of latch 120.

In order to prevent the plunger from moving forwardly under the influence of the spring 78 and the hydraulic fluid bearing against the right end of the piston 70 during cocking of the instrument, we have provided a latch which pivots about the surface 122 provided by a notch cut in the underside of the body 10. A spring 124 is disposed within a slot provided in the latch and in the handle for normally urging the latch upwardly into locked position. A trigger spring 129 also urges the latch upwardly through trigger 126. It will be noted that the surface 132 of the latch bears against the hard, wear resistant washer 93 at the front of the cup portion 76 of the plunger 72. The latch is prevented from dropping by the projection on trigger 126 which is pivotally mounted in the handle on the pin 128 extending transversely across the handle and held in latched position by wire spring 12? mounted in the handle. When the trigger is depressed as indicated in FIGURE 4, the latch drops and the plunger 72 is then able to advance to expel medicament from the chamber 18.

The actuating handle M6 for the rotary valve 40 carries a couple of wing-like stop members 144 disposed on either side thereof. These stop members are adapted to .5 contact a lever 152 which actuates a switch within the electrical switch box 148 secured to the side of the instrument. An electrical conductor 150 leads from the switch box to the source of hydraulic fluid (not shown). A solenoid operated valve in the fluid source is actuated by means of the switch lever 152. When the handle 146 is rotated counterclockwise to the position shown in FIGURE 1, the solenoid valve is opened so that hydraulic fluid will bypass the hose 139 and fiow back to the fluid reservoir. The spring 94 then expels fluid from chamber 83 as the plunger-piston assembly is retracted. At the same time, the rotary valve is disposed in the position shown in FIGURE 3 so that the medicament chamber 18 is in communication with the liquid medicament reservoir 34 through the valve port 44. Thus medicament flows in chamber 18 under suction as plunger head 72 retracts. When the handle 146 is rotated clockwise, the lever 152 is moved to its second position, opening the switch and causing the solenoid valve in theby-pass to close. The pressurized fluid is then forced into the instrument through hose 139. At the same time the rotary valve is disposed in the position shown in FIGURE 4 with the ports 42 aligned with the medicament chamber 18 and the orifice 52. Because of this construction the instrument can be discharged only when the valve is in the position shown in FIGURE 4 since this is the only time that the .pressurized fluid is permitted to enter the chamber 83.

In operation, the handle 146 is rotated counterclockwise to establish communication between the chamber 18 and the reservoir 34 as just mentioned above. At the same time, under the influence of spring 94, the hydraulic fluid in the chamber 83 is permitted to drain through the hose 139 back to the source of pressurized fluid. The

retractor spring $4 causes the plunger 72 and the piston to be fully retracted. As the plunger head 74 retracts in the medicament chamber 18, liquid is sucked from the reservoir 34 into the chamber to fill the entire space in front of the plunger head. When all of the parts are retracted, the screw 86 strikes the end fitting 15. In this position the latch 120 springs up into the position shown in FIGURE 3 so that the plunger and associated parts are locked against forward movement. As soon as the latch is in elevated position, the trigger is moved forwardly by spring 129 to support the latch and prevent it from dropping until such time as the instrument is to be fired.

When it is desired to make an injection, the handle 146 is rotated clockwise, as shown in FIGURE 4, which,

establishes communication between the medicament chamber 18 and the orifice 52 and also closes the solenoid valve so that the fluidized pressure builds up within the chamber 83 behind the piston 70. The hydraulic pressure causes the piston 70 to advance the distance indicated by the letter X, thus additionally compressing the already precompressed spring 78 this additional amount. It will be appreciated that a heavy precompressed spring will provide a powerful force upon release. It should also be pointed out that the plunger head 74 is spaced from the end of the plunger 72 a distance designated by the letter Y, which distance is less than the distance X. Now, when the trigger 126 is depressed and the latch 1% falls, the plunger 72 is immediately advanced through the distance Y under the force of the spring 78. In traversing the small distance Y the plunger picks up speed and strikes the plunger head 74 with considerable impact. This causes the liquid medicament to be expelled from the chamber 18 under great force which imparts extremely high velocity to the liquid. The high initial force is continued until the spring has expanded to the extent permitted by the link 90 which, of course, is the distance X. At this point the further advance of the plunger 72 and the head 74 is produced by hydraulic pressure imposed against the piston 70. This is a lesser force which results in the relatively lower velocity required for the follow-through in expelling the medica- 6 ment from the chamber into the tissue after the initial piercing by the high velocity jet stream.

Other modifications in the structure of the instrument will occur to those skilled in the art without departing from the principles of our invention. We intend to include such modifications as may be embraced by the appended claims.

We claim:

1. An ejector instrument comprising a hollow body closed at its forward end with a cylindrical block containing a medicament chamber, a medicament reservoir mounted on said body, a nozzle mounted on the outer end of said block, a first bore between said nozzle and said medicament chamber, a second bore between said first bore and said medicament reservoir, a rotary valve member in said first bore for establishing communication between said medicament chamber and said reservoir in one position and between said medicament chamber and said nozzle in another position, a plunger carried within said body having an enlarged rear cup-like spring seat and a head within said chamber for expelling medicament through said nozzle, a piston slidably mounted in the other end of said body, spring means precompressed between said spring seat and said piston, a link connected to said plunger to maintain said spring in a precompressed state, a latch mounted at a predetermined point on said body adjacent said plunger to lock said plunger against forward movement, and fitting means within said body behind said piston for connecting to a source of pressurized fluid for advancing said piston to additionally compress said spring means, whereby upon release of said latch said spring expands to impart the initial advancing force to the plunger and said piston continues to apply the advancing force for ejecting the medicament.

2. The instrument of claim 1 which'includes an elbow screwed into a threaded opening in said body connecting with said second bore, a flange on said elbow adjacent said body, a sealing gasket between said flange and said body and a tube connecting said elbow with said reservoir.

3. An injector instrument comprising a hollow body defining at one end a medicament chamber having a discharge orifice, a plunger carried within said body having a rear spring seat portion, a head slidably connected to the, forward end of said plunger to permit spacing said head a predetermined distance from said forward end,

. said head being disposed within said chamber for expell-ing medicament through said orifice, a piston slidably mounted in the other end of said body, means linking said plunger to said piston,- spring means interposed between said spring seat portion and said piston, a latch mounted on-said body for locking said plunger in a position slightly spaced from said piston when the latter is in retracted position, said slight space between said plunger and said piston being greater than said predetermined distance and limited by said linking means, and power means mounted in said other end of said body behind said piston and reacting against the rear end of said body for advancing said piston into engagement with said plunger to compress said spring means, whereby upon release of said latch said spring means expands to impart the initial advancing force to the plunger and said piston continues to apply the advancing force for ejecting the medicament.

4. An injector instrument for ejecting liquid at high velocity through a jet orifice by means of a plunger in its forward end, characterized by actuating means for the plunger which comprises a coil spring, disposed behind said plunger, means secured to said plunger for holding said spring in a precompressed state, a latch mounted on said instrument for locking said plunger, and power means said instrument behind said spring for further compressing said spring, whereby upon release of said latch said spring expands to impart the initial advancing force to the plunger and said power means continues to apply the advancing force for ejecting the liquid.

5. An injector instrument comprising a hollow body defining at the forward end thereof a liquid medicament chamber having a discharge orifice, a plunger mounted for reciprocative movement within said body, said plunger terminating at its forward end in a head which reciprocates within said chamber for expelling liquid therefrom and terminating at its rearward end in a spring seat, a piston slidably mounted within said body rearwardly of said spring seat, link means interconnecting said plunger and piston to limit separating movement therebetween, a spring interposed between said spring seat and said piston for advancing said plunger and said plunger head toward said orifice to the extent permitted by said link, power means mounted at the rear of said body behind said piston and reacting against the rear end of said body for advancing said piston and compressing said spring against said spring seat, a latch mounted on said body for locking said plunger against forward movement with respect to said body, thereby causing said piston to move into contact with said plunger when said power means is actuated to advance said piston, whereby upon release of said latch said spring expands to the extent permitted by said link means to impart initial advancing force to to said plunger and said piston continues to advance said plunger to expel liquid from said chamber.

6. An injector instrument comprising a hollow body defining at the forward end thereof a liquid medicament chamber having a discharge orifice, a plunger mounted for reciprocative movement within said body, said plunger terminating at its forward end in a head which reciprocates within said chamber for expelling liquid therefrom and terminating at its rearward end in a spring seat, said head being axially movable relative to said plunger, a piston slidably mounted within said body rearwardly of said spring seat, a precompressed spring interposed between said spring seat and said piston for advancing said plunger and said plunger head toward said orifice, a latch mounted on said body for locking said plunger against forward movement with respect to said body, a link between said plunger and said piston for holding said spring in the precompressed state and limiting the separating movement therebetween, and power means mounted at the rear of said body behind said piston and reacting against the rear end of said body for advancing said piston into contact with said plunger to further compress said spring when the plunger is latched, said plunger head being spaced a predetermined distance from the forward end of said plunger when the plunger is latched, whereby upon release of said latch said spring expands to the extent permitted by the link to impart initial advancing force to said plunger to cause it to strike said head by traversing said predetermined distance and said piston E5 continues to advance said plunger and said head together to expel liquid from said chamber.

7. The instrument of claim 6 in which said spring seat is round and of larger diameter than the rest of said plunger and which includes a piston retractor spring between the forward surface of said spring seat and the body portion defining said medicament chamber for retracting the plunger to latched position when the power means is inactive.

8. An injector instrument comprising a hollow body defining at its forward end a liquid medicament chamber having a discharge orifice, a plunger reciprocatively mounted in said body having a head within said chamber for expelling liquid therefrom and a spring seat at its rear end, a piston slidably mounted in the rear end of said body, a first spring interposed between said spring seat and said piston, a link between said Plunger and said piston for holding said spring in a precompressed state and for limiting the space separating said plunger and said piston, a latch mounted on said body adjacent said plunger for locking said plunger with respect to said body against movement forwardly into said medicament chamber, a second spring interposed between said spring seat and said forward end for retracting the plunger and piston behind said latch, a reservoir mounted on said body for supplying medicament to said chamber and a hose connection at the rear of the .body behind said piston for connecting to a source of pressurized fluid for compressing said first spring against the latched plunger and advancing said plunger upon release of said latch and after said spring has expanded through said limited separating space.

9. The instrument of claim 8 which includes an adjusting screw between said piston and the rear of said body to vary the position of said piston within said body in the retracted position.

10. The instrument of claim 8 which also includes sealing means extending radially between said piston and the inside of said body to seal the annular space therebetween and confine said pressurized fluid behind said piston.

11. The instrument of claim 8 in which said plunger head is detachable from the plunger proper and movable with respect thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,573,954 Casson Nov. 6, .1951 2,754,878 Scherer July 17, 1956 2,816,543 Venditty et a1 Dec. 17, 1957 2,928,390 Venditty et a1. Mar. 15, 1960 3,057,349 Ismach Oct. 9, 1962 

1. AN EJECTOR INSTRUMENT COMPRISING A HOLLOW BODY CLOSED AT ITS FORWARD END WITH A CYLINDRICAL BLOCK CONTAINING A MEDICAMENT CHAMBER, A MEDICAMENT RESERVOIR MOUNTED ON SAID BODY, A NOZZLE MOUNTED ON THE OUTER END OF SAID BLOCK, A FIRST BORE BETWEEN SAID NOZZLE AND SAID MEDICAMENT CHAMBER, A SECOND BORE BETWEEN SAID FIRST BORE AND SAID MEDICAMENT RESERVOIR, A ROTARY VALVE MEMBER IN SAID FIRST BORE FOR ESTABLISHING COMMUNICATION BETWEEN SAID MEDICAMENT CHAMBER AND SAID RESERVOIR IN ONE POSITION AND BETWEEN SAID MEDICAMENT CHAMBER AND SAID NOZZLE IN ANOTHER POSITION, A PLUNGER CARRIED WITHIN SAID BODY HAVING AN ENLARGED REAR CUP-LIKE SPRING SEAT AND A HEAD WITHIN SAID CHAMBER FOR EXPELLING MEDICAMENT THROUGH SAID NOZZLE, A PISTON SLIDABLY MOUNTED IN THE OTHER END OF SAID BODY, SPRING MEANS PRECOMPRESSED BETWEEN SAID SPRING SEAT AND SAID PISTON, A LINK CONNECTED TO SAID PLUNGER TO MAINTAIN SAID SPRING IN A PRECOMPRESSED STATE, A LATCH MOUNTED AT A PREDETERMINED POINT ON SAID BODY ADJACENT SAID PLUNGER TO LOCK SAID PLUNGER AGAINST FORWARD MOVEMENT, AND FITTING MEANS WITHIN SAID BODY BEHIND SAID PISTON FOR CONNECTING TO A SOURCE OF PRESSURIZED FLUID FOR ADVANCING SAID PISTON TO ADDITIONALLY COMPRESS SAID SPRING MEANS, WHEREBY UPON RELEASE OF SAID LATCH SAID SPRING EXPANDS TO IMPART THE INITIAL ADVANCING FORCE TO THE PLUNGER AND SAID PISTON CONTINUES TO APPLY THE ADVANCING FORCE FOR EJECTING THE MEDICAMENT. 